Similar support matrices have previously been manufactured for use in solid phase synthesis of organic compounds. See for instance Meldal, Meth. Enzymol. 289 (1997) 83-104; Barany et al., ACS Symp. Ser. 680 (poly(ethylene glycol) (1997) 239-264), Yoon-Sik et al (U.S. Pat. No. 5,466,758) and Bayer et al (U.S. Pat. No. 4,908,405). The materials in these matrices have typically been polystyrenes slightly cross-linked and derivatized to carry polyethylene glycol chains. Bayer et al (U.S. Pat. No. 4,908,405) suggests ethoxylation at any kind of nucleophilic group attached to a polystyrene, but for some unknown reasons Bayer et al prefer to start by grafting an oligoethylene chain to chloromethyl groups on the polystyrene. The key step of Yoon-Sik et al (U.S. Pat. No. 5,466,758) for producing this kind of material is to initially ethoxylate the ring thereby creating nucleophilic β-hydroxy groups that can be further ethoxylated. Bayer et al and Yoon-Sik et al limited their methods to matrices having a low degree of cross-linking (below 12%, with preference for 2-3%, of divinyl monomers in the polymerisation mixture). Nothing is said about selecting porous matrices in neither U.S. Pat. No. 4,908,405 nor U.S. Pat. No. 5,466,758. The low degree of cross-linking implies unfavourably swelling characteristics and a too low rigidity for liquid column chromatography.
Jones et al (U.S. Pat. No. 4,611,014) describe functionalization of macroporous supports obtained by polymerisetion in high internal phase emulsions (HIPE, w/o emulsions). The base polymer material obtained from an HIPE emulsion is in form of a block and the use described is as liquid absorbents. The cross-linking degree is 1-20%, with preference for 2-10%, crosslinking monomer in the polymerisation mixture. One functionalization route is to introduce polyoxyalkylene groups, for instance by reaction of the polymer with polyoxyethylene anion or by reacting a hydroxy or carboxy functionalized form with ethylene oxide.
Li et al., (WO 9533553) describe beads obtained from w/o/w-emulsions and their use for (a) absorbing acids and aqueous solutions and (b) as substrates (support matrices) in chromatography, solid phase synthesis, cell culture and the like. The cross-linking degree is in the interval 1-90% cross-linking monomers. It is suggested to attach polyoxyalkylene groups to pore surfaces if the beads are to be used for absorbing aqueous liquids.
In U.S. Pat. No. 4,611,014 and WO 9533553 polyoxyalkylene groups may be end-derivatized with a cation exchanging group (—COO−, or (—OSO2O−).
Membranes made of ethoxylated non-cross-linked condensation polymers such as polyamides and polyurethanes have been described in U.S. Pat. No. 3,472,766.
Cross-linking degree is one of many variables that determine rigidity and swellability. The concept of cross-linking is many times not well defined and is often difficult to measure. Therefore support matrices to be used in connection with column chromatography are in stead characterized as their ability to withstand pressure when a liquid is allowed to pass through a packed bed of support matrix particles or through a porous monolith of the support matrix.
Liquid column chromatography, cell culturing, stepwise solid phase synthesis of organic molecules, affinity adsorption in suspensions, solid phase catalysis with immobilized catalysts (e.g. enzymes) etc often require that substances more or less selectively or specifically shall bind/adsorb to groups on the surface of a support matrix. A high binding capacity is often preferred. The substances typically are present in aqueous liquid media. This is contrary to pure absorbents that just shall be good in absorbing large amounts of liquids, for instance water.